A modern wind turbine comprises a rotor having a hub and a plurality of wind turbine blades, which extend substantially radially from the hub. The rotor is mounted to a machine housing or a nacelle, which in turn is arranged on top of a tower. The machine housing can yaw so that it can pivot around a vertical shaft in relation to the tower, hereby being able to adjust the rotor to the direction of the wind. The rotor can be put into rotation by the wind, thereby driving one or more generators.
Wind turbine blades are often provided with a bulkhead arranged at a root end of the blade, typically located within the inboard 20% of the blade. The bulkhead has two functions. First of all, it functions as a work platform for workers when having to carry out maintenance or repair inside the blade. Second of all, it prevents internal debris from falling into the machine housing of the blade. Additionally, when mounted expediently, the bulkhead is watertight.
The bulkhead is typically glued directly on to an inner wall of the wind turbine blade. However, a wind turbine blade is subjected to large loads during operation, which causes the inboard part of the blade to ovalise. This in turn entails loads to the glue bonding, and in worst case the bulkhead may be torn loose from the inner blade wall. It is also well-known to mount the bulkhead on a bathtub-shaped flange made of steel or a fibre-reinforced composite material, which allows for small movements of the blade wall relative to the bulkhead. Such a solution is for instance known from WO09/085041. However, this solution is also encumbered by large loads to the flange and to the glue bonding between the flange and the inner blade wall. Further, the relatively stiff flange makes it difficult and tedious to mount the bulkhead and flange inside the wind turbine blade.